The present invention relates to a predictive coding system for high efficiency coding of image signals as of commercial television or video telephony through utilization of high correlation present between adjoining picture elements making up a picture.
With the existing standard television, a picture consists of frames which are transmitted at the rate of thirty per second, and each frame is made up of two consecutive fields because of interlaced scanning every other scanning line. The elements constituting the picture are called "picture elements"; in this specification, since digital processing of them is borne in mind, one sample obtained by sampling will be called a picture element. Accordingly, in this case, the position of each picture element in the picture frame depends on the sampling frequency for digitizing signals.
In conventional arts, there have been proposed an intra-field predictive coding system, an inter-field predictive coding system and an inter-frame predictive coding system to encode the sampled television signal. However, it is impossible by the conventional coding system to obtain a stable coding efficiency for still to rapidly-moving images.